As a matter of fact, the only possible way to implement the 
functionality of the AJAX Remote in a web application is the way it is 
implemented right now.

A past experiment did show, that Safari will stop any timers (and thus 
new polls for information)

- when you switch to another page

- when you switch to another application

- when you manually lock/sleep the device using the respective 
hardware button

and then resumes them when you view that particular page again. Which 
works perfectly. So if Apple decided that when there's any network 
connection - no matter how short lived it is - Mobile Safari will not 
allow the device to go to sleep, I'm afraid I can't do anything about 
it. You can always file a bugreport with Apple though, which is the 
official way to request changes/fixes/improvements:

http://bugreporter.apple.com/

Best regards, 
Felix